Simulated contrast injection medium

ABSTRACT

A medical fluid injection system may include a powered injector and a fluid reservoir that contains a simulated contrast medium. The simulated contrast medium may exhibit a fluid flow property substantially equal to that of an active contrast medium but be devoid of any active contrast agent that provides contrast during diagnostic imaging. During operation, a syringe in the powered injector may be filled with the simulated contrast medium and then evacuated to discharge the simulated contrast medium from the syringe. The simulated contrast medium may be used to test and evaluate the performance of the powered injector prior to use in a medical procedure without exposing personnel to an active contrast agent or creating medical waste that contains the active contrast agent.

TECHNICAL FIELD

This disclosure relates to injectable contrast media and, moreparticularly, to simulated injectable contrast media for testing medicalequipment.

BACKGROUND

Contrast media are used in medical settings to enhance the visibility ofbodily structures during imaging procedures. Contrast media canhighlight features that would otherwise be less distinguishable fromnearby tissue to help a clinician diagnose and treat a patient's medicalcondition. A patient is typically injected with a contrast medium beforeor during an imaging procedure and then exposed to radiation orelectromagnetic energy to generate an image of the patient's body.Example imaging techniques include X-ray, computed tomography (CT),nuclear magnetic resonance (NMR)/magnetic resonance (MR), ultrasound,fluoroscopy, and positron emission tomography (PET).

As an example, angiography is a medical procedure that usually involvesinjecting a patient with a contrast medium. Angiography is a procedureused in the diagnosis and treatment of cardiovascular conditionsincluding abnormalities or restrictions in blood vessels. Duringangiography, a radiographic image of the heart or a vascular structureis obtained by injecting a radiographic contrast medium through acatheter into a vein or artery. The injected contrast medium can pass tovascular structures in fluid communication with the vein or artery inwhich the injection is made. X-rays are then passed through the regionof the body in which the contrast material was injected. The X-rays areabsorbed by the contrast medium, causing a radiographic outline or imageof the blood vessel containing the contrast material.

When used, a contrast medium is typically injected into a patient by anautomated injection system. While the apparatus for injecting thecontrast medium can vary, most systems include a syringe operativelyconnected with a catheter. The catheter is placed into a vein or arteryof a patient. During operation, a ram forces the contrast medium out ofthe syringe, through the catheter, and into the patient at a rate andvolume determined by the speed of movement of the ram.

To ensure that an automated injection system is working properly priorto being placed in service and even after being placed in service, acontrast medium may be periodically passed through the injection systemwithout actually injecting the contrast medium into a patient. Rather,the contrast medium may be passed through the injection system tomonitor and validate the operational integrity of the injection systemwithout injecting the contrast medium into a patient. For example, thefluid integrity of various fluid reservoirs, fluid lines, and connectorsmay be monitored during a test injection to ensure that there are noleaks in the injection system. The contrast medium discharged from aninjection system during such operational testing is typically discardedafter use.

Medical contrast media are generally expensive to manufacture andchemically stable once discarded. For example, some medical contrastmedia may pass through waste water treatment plants without decomposing.Ensuring that medical injection systems can be accurately tested andvalidated while limiting consumption of contrast media to medicalprocedures may provide a variety of benefits.

SUMMARY

In general, this disclosure is directed to systems and techniques fordeveloping simulated contrast media and for operating medical fluiddelivery devices using the simulated contrast media. A simulatedcontrast medium may be a liquid that simulates the fluid flow propertiesof a traditional contrast medium introduced into a patient during animaging procedure but which does not contain active contrast agents. Forexample, a simulated contrast medium may exhibit fluid flow propertiessubstantially equal to a contrast medium containing an active contrastagent that enhances the visual contrast of structures or fluids within abody during an imaging procedure. However, the simulated contrast mediummay be devoid of any active contrast agents such that, were thesimulated contrast medium injected into the body of a patient, thesimulated contrast medium would not enhance the contrast of anystructures or fluids within the body of the patient during an imagingprocedure. Of course, a clinician would not actually inject thesimulated contrast medium into a patient during hardware testing. Byreplicating the fluid flow properties of a contrast medium that containsan active contrast agent, the simulated contrast medium may imitate theflow behavior and injection characteristic of the contrast medium.Accordingly, the simulated contrast medium can be used to reliably testand validate the operational integrity of an injection system andrelated hardware/software. Yet because the simulated contrast mediumdoes not contain an active contrast agent, the simulated contrast mediumcan be handled without exposing workers to the active contrast agent anddisposed of without introducing the active contrast agent into theenvironment.

In one example, a system is described that includes a powered injector,a fluid reservoir, and a processor. The powered injector includes aplunger, a motor configured to advance and retract the plunger, and asyringe holder configured to hold a syringe so that the plunger moveswithin the syringe. The fluid reservoir contains a simulated contrastmedium in fluid communication with the syringe. According to theexample, the simulated contrast medium exhibits a fluid flow propertyequivalent to that of an active contrast medium but is devoid of anyactive contrast agent that provides contrast during diagnostic imaging.The processor is configured to retract the plunger within the syringe soas to draw the simulated contrast medium from the reservoir into thesyringe and advance the plunger within the syringe so as to dischargethe simulated contrast medium from the syringe.

In another example, a method is described that includes connecting afluid reservoir containing a simulated contrast medium to a syringe of apowered injector. The simulated contrast medium exhibits a fluid flowproperty equivalent to that of an active contrast medium but is devoidof any active contrast agent that provides contrast during diagnosticimaging. The example method also includes performing a fill operation bymoving, under the control of a processor, a plunger of the poweredinjector rearward to draw the simulated contrast medium from the fluidreservoir into the syringe. The example method further includesperforming an injection operation by moving, under the control of theprocessor, the piston of the powered injector forward to discharge thesimulated contrast medium from the syringe.

In another example, a method is described that includes injecting, underthe control of one or more processors, a contrast medium through acatheter so as to generate data indicative of a pressure of the contrastmedium versus time and injecting, under the control of the one or moreprocessors, a simulated contrast medium through the catheter so as togenerate data indicative of a pressure of the simulated contrast mediumversus time. The simulated contrast medium includes a simulated contrastagent and a diluent. According to the example, the method furtherincludes comparing, by the one or more processors, the pressure of thecontrast media to the pressure of the simulated contrast media andadjusting a concentration of the simulated contrast agent in thesimulated contrast media based on the comparison.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of example medical fluid injection system.

FIG. 2 is a functional block diagram illustrating example components ofthe medical fluid injection system of FIG. 1.

FIG. 3 is a block diagram showing an example contrast fill operationthat may be performed using the system of FIGS. 1 and 2.

FIG. 4 is a block diagram showing an example air purge operation thatmay be performed using the system of FIGS. 1 and 2.

FIG. 5 is a block diagram showing an example contrast injectionoperation that may be performed using the system of FIGS. 1 and 2.

FIG. 6 is a flow diagram of an example technique for preparing asimulated contrast medium.

FIGS. 7A-7C are pressure versus time profiles for an example contrastmedium containing an active contrast agent.

FIGS. 8A-8C are pressure versus time profiles for an example simulatedcontrast medium having a first concentration of a simulated contrastagent.

FIGS. 9A-9C are pressure versus time profiles for an example simulatedcontrast medium having a second concentration of a simulated contrastagent.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes may be provided for selected elements, and allother elements employ that which is known to those of skill in the fieldof the invention. Those skilled in the art will recognize that many ofthe examples provided have suitable alternatives that can be utilized.

A powered medical fluid injector may be used to inject a contrast mediuminto the body of a patient during a diagnostic imaging procedure. Thecontrast medium may contain an active contrast agent that interacts withradiation or electromagnetic energy from a diagnostic imaging machine toenhance the visual contrast of structures or fluids within a body of thepatient, for example, as compared to structures or fluids not exposed tothe contrast agent. For example, the contrast agent may highlightfeatures that would otherwise be less distinguishable from nearby tissueto help a clinician diagnose and treat a patient's medical condition.

To ensure that a powered medical fluid injector and/or related hardwareare operating properly prior to being placed in service and, in someapplications, even after being placed in service, the injector and/orrelated hardware may be tested by filling the injector with contrastmedium and then operating the injector to discharge the contrast mediumfrom the injector. Unlike injection during a diagnostic imagingprocedure, however, the contrast medium is not discharged from theinjector into a patient. Instead, the contrast medium is discharged fromthe injector into a waste receptacle. The test injection may be used toconfirm that various components of the injector such as a motor andgears are operating properly and that the fluid connections in theinjector provide fluid integrity for the system. The test injection mayalso be used to confirm that tubing lines (e.g., part of apatient-specific tubing kit) are fluid tight and can withstand fluidpressures generated during an injection procedure.

While contrast medium with an active contrast agent can be used to testthe performance of an injector and related hardware outside of a medicalprocedure, use of the contrast medium may expose test personnel to theactive agent and create waste that is difficult to dispose of. In someexamples, this disclosure describes systems and techniques that employ asimulated contrast medium for testing a powered medical fluid injectorand related hardware. The simulated contrast medium may exhibit fluidflow properties equivalent to that of an active contrast medium but bedevoid of any active contrast agent that provides contrast duringdiagnostic imaging. For example, the simulated contrast medium may beconfigured such that, were the simulated contrast medium injected into apatient, the simulated contrast medium would not cause a contrastbetween structures or fluids infused with the simulated contrast mediumand adjacent structures or fluids not infused with the simulatedcontrast medium.

By replicating the fluid flow properties of the active contrast medium,an injector using the simulated contrast medium may exhibit operationalperformance similar to how the injector would perform, were the injectorusing the active contrast medium. Further, because the simulatedcontrast medium does not contain active contrast agent, the simulatedcontrast medium may be handled and disposed of without the risksassociated with the active contrast medium.

To develop a simulated contrast medium for a particular application, acontrast medium with an active contrast agent may first be passedthrough a powered injector to develop fluid flow characteristic data forthe medium. Thereafter, a working formulation of the simulated contrastmedium may be passed through the powered injector to developcorresponding fluid flow characteristic data for the working formulationof the simulated contrast medium. After comparing the fluid flowcharacteristic data of the working formulation of the simulated contrastmedium to the fluid flow characteristic data of the active contrastmedium, the composition of the simulated contrast medium may be adjusteduntil its fluid flow characteristics are substantially equal to that ofthe active contrast medium. In this manner, a simulated contrast mediummay be produced that exhibits one or more fluid flow propertiessubstantially equal to that of the active contrast medium.

Example systems and methods for formulating a simulated contrast mediumare described in greater detail below with respect to FIGS. 6-9.However, an example system that includes a powered injector that mayinject a simulated contrast medium will first be described withreference to FIGS. 1-5.

FIG. 1 is a perspective illustration of an example contrast mediuminjector system 10, which may be used to inject contrast medium into apatient under interactive physician control during a medical procedure,such as an angiogram. As described in greater detail below, contrastmedium injector system 10 may also be used to inject a simulatedcontrast medium, e.g., to test and validate the operational integrity ofthe system. In the example of FIG. 1, system 10 includes main console12, hand held remote control 14, syringe holder 16, syringe 18, syringeplunger 20, contrast medium reservoir (e.g., bottle) 22, inlet valvesystem 24, manifold 26, high pressure tube 28, catheter 30, patientmedication port 32, three-way stop-cock 34, T-connector 36, pressuretransducer 38, stop-cock 40, tubing 42, peristaltic pump 44, salinecheck valve 46, saline reservoir 50, and reservoir support rack 53.Contrast medium injection system 10 is only one example of aconfiguration of a powered injector that can be used in accordance withthe disclosure. In other examples, contrast medium injector system 10may include a second syringe holder, a second syringe main body, and asecond syringe plunger in communication with a saline reservoir insteadof the peristaltic pump shown in FIG. 1.

In the example of FIG. 1, console 12 houses the electrical controls forsystem 10, together with the motor(s) which drive plunger 20 andperistaltic pump 44. Console 12 includes a user interface 54 thatprovides control switches 56 and display 58 through which a user mayenter control settings and monitor the operational state of system 10.

Remote control 14 can be connected to console 12 by cable 60 (althoughin other examples remote control 14 may be connected by a wirelessconnection such as an RF, infrared optic, or ultrasonic link). Remotecontrol 14 is, in the example of FIG. 1, a hand-held control whichincludes reset and saline push button switches 62 and 64, respectively,and flow rate control lever or trigger 66. By squeezing trigger 66, theuser can provide a command signal to console 12 to control the rate atwhich medial fluid is discharged from syringe 18 and injected intocatheter 30. In other examples, system 10 does not include remotecontrol 14. In these examples, a user may control the operation ofsystem 10 directly via console 12.

Syringe holder 16 in the example of FIG. 1 projects from the left handside of console 12. Syringe holder 16 is configured to receive and holda removable syringe. Syringe holder 16 may be fabricated from clearmaterial and may open to receive a syringe and close to hold the syringewithin a bounded cavity. In system 10, syringe holder 16 includes a halfcylindrical back shell 68, a half cylindrical front door 70 (which isshown in open position in FIG. 1), and reservoir holder 72. A user mayopen half cylindrical front door 70, insert a disposable syringe 18 sothat the syringe is positioned against half cylindrical back shell 68,and then close half cylindrical front door 70 so that the syringe issecured within syringe holder 16.

Syringe 18 is inserted into syringe holder 16 and defines an open end 74connected to console 12 and a closed end 74 opposite the open end.Closed end 74 of syringe 18 contains at least one port which, in theillustrated example, is shown as two ports: inlet port 78 and outletport 80. Inlet port 78 is in fluid communication with contrast mediumreservoir 22. Outlet port 80 is in fluid communication with highpressure tube 28 which, in turn, is in fluid communication with catheter30. Syringe 18 may or may not be fabricated from a transparent ortranslucent material such as plastic or glass.

During operation, plunger 20 is configured to advance and retractaxially along the length of syringe 18. For example, starting withplunger 20 positioned inside of syringe 18 and fluid communication withhigh pressure tube 28 closed, the piston may be retracted (e.g., bywithdrawing the piston from left to right in FIG. 1) to draw contrastmedium from contrast medium reservoir 22 into syringe 18 via inlet port78. Thereafter, fluid communication between contrast medium reservoir 22and syringe 18 via inlet port 78 may be closed and fluid communicationbetween the syringe and high pressure tube 28 via outlet port 80 opened.Advancing plunger forward within syringe 18 may compress liquid fluid(e.g., contrast medium) within the syringe, causing the fluid todischarge under pressure from the syringe into catheter 30.

In FIG. 1, contrast medium reservoir 22 is connected to inlet port 78through inlet valve system 24. During operation, contrast medium isdrawn from reservoir 22 through inlet valve system 24 and inlet port 78into the pumping chamber defined by syringe 18 and plunger 20. Inletvalve system 24 may be a one-way valve that permits air to flow fromsyringe 18 back into reservoir 22 but which will not permit contrastmedium to flow from syringe 18 to reservoir 22 when fully closed.

Outlet port 80 of syringe 18 in FIG. 1 is connected to manifold 26.Manifold 26 may include a spring biased spool valve which normallyconnects a saline port 82 and patient port 84. When contrast medium isbeing injected, the pressure of the contrast medium may cause the spoolvalve to change states so that outlet port 80 is connected to patientport 84 (i.e., as opposed to saline port 82). Other types of valvesbesides spring biased spool valves that selectively communicate betweenthe contrast medium and the saline can be used, and the disclosure isnot limited in this respect.

High pressure tube 28 in system 10 is a flexible tube connecting patientport 84 to catheter 30. A three-way stop-cock 34 is located at thedistal end of tube 28. A rotatable luer lock connector 86 is connectedto stop-cock 34 and mates with luer connector 88 at the proximal end ofcatheter 30. A stopcock 34 either blocks flow between tube 28 andcatheter 30, permits flow, or connects medication port 32 to catheter 30(for use when medication is to be delivered through catheter 30 to thepatient).

To enable a user to monitor the performance of contrast medium injectionsystem 10 during an injection operation, the system may include apressure sensor or other monitoring hardware. In the example of FIG. 1,system 10 includes pressure transducer 38 that is configured to monitorblood pressure of a patient. When catheter 30 is placed within a patientand injection of contrast medium is not taking place, pressuretransducer 38 can monitor the patient's blood pressure through a columnextending from the patient through catheter 30, tube 28, patient port84, manifold 26, saline port 82, tubing 90, T-connector 36, and tubing92. In the example shown, transducer 38 has an associated stop-cock 40which allows transducer 38 to be exposed to atmospheric pressure duringcalibration and also allows for removal/expulsion of trapped air so thedome chamber of transducer 38 can be flushed with saline.

In some examples, system 10 also includes a pressure sensor (e.g., apressure transducer) configured to measure a pressure of the contrastmedium as the contrast medium is discharged from syringe 18. Forexample, system 10 may include a pressure transducer that is separatefrom pressure transducer 38 configured to measure a patient's bloodpressure. The pressure transducer may measure a pressure of the contrastmedium as the contrast medium is discharged from syringe 18 fordeveloping simulated contrast medium formulations. When used, thepressure sensor may be in fluid communication with outlet port 80 and/orcatheter 30 and configured to measure the pressure of the contrastmedium during high pressure injection. In one example, the pressuresensor is configured to measure a pressure of a contrast medium (and/ora simulated contrast medium) at a location between high pressure tube 28and catheter 30. Data from the pressure sensor may indicate to a userthe pressure at which contrast medium is forcibly injected into apatient during operation and/or the pressure at which a simulatedcontrast medium would be forcibly injected into a patient, were thesimulated contrast medium being injected into a patient. As noted abovethrough, a clinician would not actually inject the simulated contrastmedium into a patient when testing hardware.

System 10 in the example of FIG. 1 also includes peristaltic pump 44.Peristaltic pump 44 supplies saline solution from reservoir 50 throughsaline check valve 46, tubing 42, T-connector 36 and tubing 90 to salineport 82. When peristaltic pump 44 is operating to supply salinesolution, the saline solution may be supplied through manifold 26 topatient port 84 and then through tube 28 to catheter 30. In otherexamples, system 10 does not include peristaltic pump 44. Rather, inthese examples, system 10 may include a second syringe and plungerassembly that is in selective fluid communication with catheter 30. Theplunger may retract and advance within the second syringe to draw salineinto the syringe and discharge the saline from the syringe into catheter30, similar to the process described above with respect to syringe 18and plunger 20.

In use, a user may enter into system 10 the safety parameters that willapply to the injection of radiographic contrast material. These safetyparameters typically include the maximum amount of radiographic contrastmaterial to be injected during any one injection, the maximum flow rateof the injection, the maximum pressure developed within syringe 18, andthe maximum rise time or acceleration of the injection. To actuate aninjection of contrast material, the user may operate remote control 14by squeezing trigger 66. Within the preset safety parameters, system 10causes the flow rate of the injection to increase as the force ordistance of travel of trigger 66 is increased.

FIG. 2 is a functional block diagram illustrating components an exampleof contrast medium injection system 10, which includes syringe 18,plunger 20, catheter 30, and outlet port 80 previously described withrespect to FIG. 1. Injection system 10 in the example of FIG. 2 alsoincludes a pressure sensor 100, a motor 102, a processor 104, and amemory 108. Processor 104 is communicatively coupled to pressure sensor100, motor 102, and memory 108. Pressure sensor 100 is configured tomeasure the pressure of contrast medium discharged from syringe 18during high pressure injection, e.g., for developing simulated contrastmedia formulations. Motor 102 is configured to advance and retractplunger 20 within syringe 18, e.g., for filling the syringe withcontrast medium and discharging the contrast medium form the syringeinto catheter 30.

During operation of contrast injection system 10, processor 104 controlsthe filling and discharge of contrast medium from syringe 18 with theaid of instructions associated with program information stored in memory108. Processor 104 may also control the filling and discharge ofcontrast medium from syringe 18 based on instructions received from auser, e.g., via main console 12 and/or hand held remote control 14 inFIG. 1. Instructions executed by processor 104 may, for example, definefluid delivery programs that specify the quantity, rate, and/or pressurewith which contrast medium is to be delivered from syringe 18 intocatheter 30 during a diagnostic imaging procedure and/or duringoperational testing of system 10. Instructions executed by processor 104may also control the opening and closing of valves within system 10 tofill syringe 18 with contrast medium and to discharge the contrastmedium from the syringe.

Processor 104 of contrast medium injection system 10 may each includeone or more processors, such as one or more microprocessors, digitalsignal processors (DSPs), application specific integrated circuits(ASICs), field programmable gate arrays (FPGAs), programmable logiccircuitry, or the like, either alone or in any suitable combination. Ingeneral, processor 104 may receive electrical signals from input devicessuch as remote control 14 and front panel controls 56 and provideelectrical signals to output devices such as display 58 and motor 102.For example, processor 104 may provide signals to display 58 that causethe display to display operation data, alerts, status information, andoperator prompts. As another example, processor 104 may provide signalsto motor 102 to control the advancing and retracting motion of plunger20 through a motor drive circuit.

Memory 108 may store instructions and related data that, when executedby processor 104, cause contrast injection system 10 and processor 104to perform the functions attributed to them in this disclosure. Forexample, memory 108 of contrast injection system 10 may storeinstructions for execution by processor 104 including, e.g., commandsfor actuating valves, instructions for filling and/or dischargingsyringe 18, instructions for monitoring and comparing a signal generatedby pressure sensor 100, and any other information regarding the system10.

Contrast medium injection system 10 in the example of FIG. 2 alsoincludes pressure sensor 100. Pressure sensor 100 is configured tomeasure a pressure of the contrast medium as the contrast medium isdischarged from syringe 18. For example, pressure sensor 100 may measurea pressure of the contrast medium at the discharge end of syringe 18 soas to generate indicative of pressure of the discharged contrast mediumversus time. The data may indicate how the discharge pressure of thecontrast medium varies over time during an injection operation, e.g., asplunger 20 advances through syringe 18 (e.g., from right to left in theexample of FIG. 2). Processor 104 may receive data from pressure sensor100 and store the data in memory 108.

While pressure sensor 100 is shown in FIG. 2 as being contained withincontrast medium injection system 10 and in direct communication withprocessor 104, it should be appreciated that the depiction of thepressure sensor in this configuration is for descriptive purposes only.The functionality of the hardware and software of contrast mediuminjection system 10, including pressure sensor 100, may be realized byseparate hardware, firmware, or software components that, incombination, perform the functions attributed to the components in thisdisclosure. Further, in still other examples, contrast medium injectionsystem 10 does not include pressure sensor 100. Instead, in theseexamples, contrast medium injection system 10 may determine a pressureof a contrast medium (or simulated contrast medium) during high pressureinjection indirectly rather than through direct pressure measurement.For example, system 10 may measure the amount of current motor 102requires to advance plunger 20 and determine, based on the measuredcurrent, the pressure of the contrast medium during injection. The moremotor current, the higher the pressure.

In some examples, processor 104 or a processor of a different computingdevice may be configured to analyze a signal indicative of a contrastmedium injection pressure such as a signal generated by pressure sensor100. For example, as discussed in greater detail below, processor 104 ora processor of a different computing device may analyze a signalgenerated by pressure sensor 100 for generating a simulated contrastmedium. The analysis may indicate to a user how the composition of thesimulated contrast medium should be adjusted to better match theproperties of an active contrast medium the simulated contrast medium isdesigned to simulate.

Contrast medium injection system 10 in the example of FIGS. 1 and 2 mayperform a variety of operations under the control of processor 104.Example operations includes contrast fill, air purge, and injectoperations. In different applications, system 10 can also be configuredto perform many other types of operations including, for example, salineflush and patient pressure monitoring operations.

FIG. 3 is a block diagram showing an example contrast fill operationthat may be performed using system 10. In response to control signalsfrom processor 104, motor 102 (FIG. 2) may retract plunger 20 withinsyringe 18 to draw contrast media from reservoir 22 and fill thesyringe. The contrast fill operation may be performed during initial setup of system 10, e.g., before a diagnostic imaging procedure, and/orbefore testing contrast medium injection system 10 to ensure that thesystem is working properly. During the filling operation, plunger 20 mayinitially be driven to its furthest forward position adjacent closed end76 (FIG. 1) of syringe 18. This will expel to the atmosphere themajority of the air which is located within syringe 18. Plunger 20 isthen retracted within syringe 18, creating a vacuum within the syringethat draws contrast from reservoir 22 through inlet valve system 24 andinto syringe 18 via inlet port 78.

In some examples, the contrast fill operation results in some air beingdrawn into or remaining within syringe 18. To prevent air within syringe18 from being injected into a patient through catheter 30 during apatient injection operation, the air may be purged from the syringeprior to injecting contrast medium into the patent. FIG. 4 is a blockdiagram showing an example air purge operation that may be performedusing system 10.

During an air purge operation as illustrated in FIG. 4, processor 104controls motor 102 to advance plunger 20 forward, expelling trapped airfrom within syringe 18. The air, being lighter than the contrast medium,may collect near the top of syringe 18 adjacent outlet port 80. Asplunger 20 moves forward, the air can be expelled from syringe 18through inlet port 78 and inlet valve system 24. In some examples, inletvalve system 24 allows flow of contrast media from reservoir 22 to inletport 78, but will not allow contrast media to flow in the oppositedirection from inlet port 78 to reservoir 22. Inlet valve system 24 may,however, allow air to flow from port 78 to reservoir 22 until sufficientpressure builds in the syringe to close the inlet valve system.

FIG. 5 is a block diagram showing an example contrast injectionoperation that may be performed using system 10. As shown in thisexample, processor 104 controls motor 102 to advance plunger 20 forward,creating hydraulic pressure to force contrast material out of syringe 18through outlet port 80 and through manifold 26 and high pressure tube 28into catheter 30. In some examples, processor 104 controls motor 102 inresponse to commands received from a user, e.g., via main console 12and/or hand held remote control 14. The commands may dictate the rateand/or volume of contrast medium to be discharged from syringe 18 andinjected out of outlet port 80. In some examples, as shown in FIG. 5,syringe outlet port 80 and patient port 84 are connected for fluid flowduring the patient inject operation.

When configured with manifold 26, the manifold may contain a valve thatcontrols the routing of fluid connections between patient port 84 andeither syringe outlet port 80 or saline port 82. In some examples,manifold 26 includes a spool valve which is spring biased so thatpatient port 84 is normally connected to saline port 82. When thepressure at syringe outlet port 80 builds with the movement of plunger20 forward, the bias force against the spool valve is overcome so thatsyringe outlet port 80 is connected to patient port 84, and saline port82 is disconnected from the valve within manifold 26. The spool valvemay open automatically during the patient inject operation in responseto increase pressure exerted on it from the syringe outlet port 80. Inaddition, the spool valve may close and return to its original positionallowing for connection of patient port 84 to transducer 38 when aslight vacuum is applied by retraction of plunger 20 at the end of eachpatient inject operation. In other examples, the valve within manifold26 may be an electromechanical or motor driven valve that is actuated atappropriate times to connect either syringe outlet port 80 or salineport 82 to patient port 84. In such examples, the actuator mechanism canbe controlled by console 12.

When injecting a contrast medium that contains an active contrast agentinto a patient, patient port 84 may be connected to (e.g., in fluidcommunication with) a catheter that is inserted into the patient. Thiswill deliver the contrast medium from the injector to the patient. Bycontrast, when injecting a simulated contrast medium that does notinclude an active contrast agent, patient port 84 may be in fluidcommunication with a waste reservoir (e.g., a waste receptacle, adrain). This will allow the simulated contrast medium to be disposed ofafter passing through the injector.

During operation of contrast medium injection system 10, syringe 18 maybe filled with any suitable type of contrast medium and then dischargedto inject pressurized contrast medium through outlet port 80. The typeof contrast medium used for a particular application may depend on avariety of factors such as, e.g., the physiological condition of thepatient and the type of diagnostic imaging procedure the patient isundergoing. In general, when injected during a diagnostic imagingprocedure, the contrast medium contains an active contrast agent thatinteracts with radiation or electromagnetic energy from a diagnosticimaging machine to enhance the visual contrast of structures or fluidswithin a body of the patient, e.g., as compared to structures or fluidsnot exposed to the contrast agent.

In some examples, the active contrast agent is a radiopaque agent thatis opaque to x-rays or similar radiation. For example, the activecontrast agent may be an organically (i.e., non-ionic) ornon-organically (i.e., ionic) bound molecule, such as organically ornon-organically bound iodine. Example iodine-based contrast mediainclude diatrizoate (Hypaque™ 50), metrizoate (Isopaque 370), ioxaglate(Hexabrix), iopamidol (Isovue® 370), iohexol (Omnipaque™ 350), ioxilan(Oxilan® 350), iopromide (Ultravist® 370), and iodixanol (Visipaque™320). Other example radiopaque agents include barium-based agents suchas barium sulfate. In still other examples, the active contrast agentmay be a radioisotope that can be detected during nuclear magneticresonance imaging or a positron emitting isotope that can be detectedduring positron emission tomography. The type of contrast medium used insystem 10 can be established by placing a selected type of contrastmedium in reservoir 22 (FIG. 1) for injection via syringe 18.

To ensure that contrast medium injection system 10 is operating properlyprior to being placed in service and, in some applications, even afterbeing placed in service, the injector may be tested by filling reservoir22 with contrast medium and then operating the injector to discharge thecontrast medium from the injector. Unlike injection during a diagnosticimaging procedure, however, the contrast medium is not discharged fromthe injector into a patient. Instead, the contrast medium is dischargedfrom the injector into a waste receptacle. The test injection may beused to confirm that various components of the injector such as a motorand gears are operating properly and that the fluid connections in theinjector provide fluid integrity of the system.

While contrast medium with an active contrast agent can be used to testthe performance of an injector outside of a medical procedure, use ofthe contrast medium may expose test personnel to the active agent andcreate waste that is difficult to dispose. For these and other reasons,contrast medium injection system 10 may, in accordance with someexamples, operate using a simulated contrast medium rather than acontrast medium with an active contrast agent. The simulated contrastmedium may simulate the behavior of the contrast medium, e.g., duringthe filling of syringe 18 and discharge from the syringe, but may lackan active contrast agent that provides visual contrast in a diagnosticimaging procedure.

When the simulated contrast medium replicates the behavior of the activecontrast medium in the injector, an operator can use the simulatedcontrast medium to accurately evaluate the operational performance ofsystem 10 without having the handling and disposal risks associated withthe active contrast medium. For example, an operator can load thesimulated contrast medium into reservoir 22 and engage contrast mediuminjection system 10 to perform one or more syringe fill and dischargeprocedures. During the syringe fill and discharge procedures, theoperator may monitor various fluid connections and hardware (e.g., motor102 and gears) in system 10 to detect any issues that may warrantattention before placing the system in service. In this way, thesimulated contrast medium can be used to evaluate the operationalintegrity of contrast medium injection system 10 without having therisks attendant to working with active contrast media.

Depending on the configuration of the simulated contrast medium, thesimulated contrast medium may be devoid of any active contrast agentsthat provide contrast during diagnostic imaging. For example, thesimulated contrast medium may not have any atoms or molecules thatfunction to provide contrast during imaging added to the medium. In theexample of a contrast medium that includes an iodine-base activecontrast agent, for instance, the simulated contrast medium may bedevoid of iodine. In some examples, the simulated contrast medium isdevoid of the atoms or molecules that function to provide contrastduring imaging by having less than 0.1 wt % of the atoms or moleculessuch as, e.g., less than 0.01 wt %, or zero weight percent. In someexamples, the concentration of an atom or molecule in a simulatedcontrast medium that functions to provide contrast during imaging may besuch that, were the simulated contrast medium injected into a patient,the simulated contrast medium would not cause a contrast betweenstructures or fluids infused with the simulated contrast medium andadjacent structures or fluids not infused with the simulated contrastmedium. For example, the atom or molecule in the simulated contrastmedium may not cause contrast during a diagnostic imaging procedureincluding, but not limited to, X-ray, computed tomography (CT), nuclearmagnetic resonance (NMR)/magnetic resonance (MR), ultrasound,fluoroscopy, and positron emission tomography (PET). Were the simulatedcontrast medium to be exposed to radiation or electromagnetic energyfrom a diagnostic imaging machine, the simulated contrast medium may betransparent to the radiation or electromagnetic energy so that thesimulated contrast medium does not provide contrast.

The specific composition and characteristics of a simulated contrastmedium suitable for use in contrast medium injection system 10 may vary,e.g., based on the type of active contrast media intended to be used inthe system during medical procedures. In some examples, the simulatedcontrast medium is configured to exhibit at least one (and, optionally,multiple) flow property equal or substantially equal to that of anactive contrast medium intended to be injected during a diagnosticprocedure using injection system 10. Example flow properties include,but are not limited to, viscosity, surface tension, pressure of thefluid during injection (e.g., a maximum pressure during injection), anddensity. In some additional examples, the simulated contrast medium isconfigured to exhibit at least one (and, optionally, multiple) otherproperty equal or substantially equal to that of an active contrastmedium intended to be injected during a diagnostic procedure usinginjection system 10, such as electrical conductivity and/or thermalconductivity. A property of a simulated contrast medium may be equal orsubstantially equal to a property of a contrast medium with an activecontrast agent in that the property of the simulated contrast medium maybe equal or substantially equal to the corresponding property of theactive contrast medium. For example, depending on the application, aproperty of a simulated contrast medium may be within a range of plus orminus 25% of a corresponding value of an active contrast medium such as,e.g., with a range of plus or minus 15% of a corresponding value, arange of plus or minus 5% of a corresponding value, or a range of plusor minus 1% of a corresponding value.

By configuring a simulated contrast medium so that it exhibits a flowproperty equal or substantially equal to that of an active contrastmedium, the simulated contrast medium may imitate the flow behavior andinjection characteristic of the active contrast medium during operationof system 10. Accordingly, the simulated contrast medium can be used toreliably test and validate the operational integrity of an injectionsystem and/or related hardware such as a patient disposable tubing kit.If the simulated contrast medium does not exhibit a flow property equalor substantially equal to that of the active contrast medium, contrastinjection system 10 may behave differently during the filling of syringe18 and injection of the simulated contrast medium, e.g., into catheter30. For example, the simulated contrast medium may not provide the sameback pressure when being pushed through outlet port 80 and catheter 30by plunger 20 as compared to when syringe 18 is filled with an activecontrast medium. In turn, operation of injection system 10 with thesimulated contrast medium in this example may not accurately indicate toan operator how the system will behave in subsequent use with an activecontrast agent.

A simulated contrast medium configured to be used in contrast mediuminjection system 10 can be formed of any suitable chemical components.In general, the specific chemical components used in the medium will beselected so that the simulated contrast medium exhibits a flow propertyequal or substantially equal to that of an active contrast mediumintended to be used in system 10. In some examples, the simulatedcontrast medium includes a diluent and a simulated contrast agent. Thediluent may be a bulk liquid component that forms a majority of theweight of the simulated contrast agent. The simulated contrast agent maybe a component that does not provide contrast during an imagingprocedure but rather modifies a flow property of the simulated contrastmedium so that the flow property is equal or substantially equal to thatof an active contrast medium. Depending on the application, thesimulated contrast agent may also be referred to as a property modifier(e.g., a flow property modifier).

In one example, the simulated contrast medium includes water as adiluent and an organic polymer as a simulated contrast agent. Theorganic polymer may be added to the water to a weight percentagesufficient to cause the simulated contrast medium to exhibit a flowproperty (e.g., viscosity) equal or substantially equal to that of acontrast medium that contains an active contrast agent. Example organicpolymers that may be used in the simulated contrast medium include, butare not limited to, polyvinyl alcohol, polyethylene glycol, and starch.In different examples, the organic polymer may range from approximately0.1 wt % to approximately 10 wt % of the simulated contrast medium suchas, e.g., from approximately 1 wt % to approximately 5 wt % of thesimulated contrast medium.

In some examples, the simulated contrast medium includes (or,optionally, consists or consists essentially of) polyvinyl alcohol andwater. The polyvinyl alcohol may range from approximately 0.1 wt % toapproximately 10 wt % of the simulated contrast medium such as, e.g.,from approximately 1 wt % to approximately 5 wt % of the simulatedcontrast medium. An example polyvinyl alcohol that may be suitable foruse in the simulated contrast medium is a polyvinyl alcohol manufacturedunder the tradename Elvanol 71-30 by DuPont®.

In general, contrast media that contain active contrast agents exhibitviscosities greater than that of water. Accordingly, in applications inwhich a simulated contrast medium is formulated to exhibit a viscosityequal or substantially equal to that of a contrast medium that containsan active contrast agent, the simulated contrast medium may also exhibita viscosity greater than that of water. In different examples, thesimulated contrast medium may exhibit a viscosity greater than 1centipoise (cp) such as, e.g., a viscosity greater than approximately1.5 cp. In some examples, the simulated contrast medium exhibits aviscosity range from approximately 1 cp to approximately 50 cp such as,e.g., a viscosity ranging from approximately 1.5 cp to approximately 25cp. The foregoing viscosity values are merely examples, however, and itshould be appreciated that a simulated contrast medium in accordancewith the disclosure is not limited in this respect.

As examples, some commercially available contrast media exhibit thefollowing viscosities: IOMERON 150 (viscosity of 1.4 cP at 37 degreesCelsius), RENO-60 (viscosity of 4.0 cP), ISOVUE-370 (viscosity of 20.29cP), and IOMERON-400 (viscosity of 27.5 cP). Therefore, in instances inwhich a simulated contrast medium is formulated to exhibit a viscosityequal or substantially equal to one or more of the foregoing activecontrast media, the simulated contrast medium may exhibit a viscosityequal or substantially equal to any one or more of the foregoing activecontrast media.

In different examples, a contrast medium with an active contrast agentmay behave as an isotropic Newtonian fluid or a thixotropicNon-Newtonian fluid. In an isotropic Newtonian fluid, the viscosity ofthe fluid is relatively constant as the fluid undergoes time-dependentshear stress. On the other hand, thixotropic Non-Newtonian fluidtypically exhibit time-dependent changes in viscosity, where the longerthe fluid undergoes shear stress, the lower its viscosity. This effectis sometimes referred to as shear thinning.

In instances in which a simulated contrast medium is intended tosimulate an active contrast medium that behaves as a thixotropic fluid,the simulated contrast medium may also exhibit thixotropic behavior. Byconfiguring the simulated contrast medium so that it exhibits the sameor similar viscosity behavior as the active contrast medium, thesimulated contrast medium may better imitate the filling and dischargebehavior of the active contrast medium during operational testing.

A variety of different contrast injection system configurations andcontrast media have been described with respect to FIGS. 1-5. FIG. 6 isa flow diagram of an example technique for preparing a simulatedcontrast medium. For ease of description, the technique of FIG. 6 willbe described with reference to contrast injection system 10 andprocessor 104 (FIGS. 1 and 2). Further, the technique of FIG. 6 will bedescribed with reference to an example simulated contrast medium thatincludes polyvinyl alcohol and is designed to simulate an activecontrast medium that includes organically bound iodine. It should beappreciated that technique of FIG. 6 may be performed using differentcontrast injection systems and computing devices as described herein. Inaddition, it should be appreciated that the techniques of FIG. 6 may usea simulated contrast medium having a different composition and/or isdesigned to simulate an active contrast medium having a different activecontrast agent. The disclosure is not limited in these respects.

In the example of FIG. 6, pressure data is generated by injecting acontrast medium containing organically bound iodine through outlet port80 from syringe 18 (200). Syringe 18 is filled with the organicallybound iodine contrast medium from reservoir 22 during a fill operation.Subsequently, processor 104 controls motor 102 to advance plunger 20into syringe 18 and discharge the contrast medium through outlet port 80and, in some examples, into catheter 30. Pressure sensor 100 may measurethe pressure of the contrast medium as the medium is ejected from thesyringe so as to generate data indicative of how the discharge pressureof the contrast medium varies over time during the injection. Forexample, the data may indicate the pressure at outlet port 80 from aninitial time when plunger 20 starts to advance within syringe 18 to afinal time when the plunger stops advancing within the syringe.Depending on the configuration of injection system 10, a maximumpressuring during an injection operation may be greater than 400 poundsper square inch (psi) such as greater than 500 psi, greater than 800psi, or even greater than 1000 psi. Processor 104 may receive the datafrom pressure sensor 100 and store the data as active contrast mediumpressure data in memory 108.

Subsequent to generating pressure data from the contrast mediumcontaining organically bound iodine, pressure data is generated from asimulated contrast medium that includes water as a diluent and polyvinylalcohol as a simulated contrast agent (202). Syringe 18 is filled withthe simulated contrast medium from reservoir 22 during a fill operation.Reservoir 22 initially filled with active contrast medium may bereplaced with a reservoir filled with the simulated contrast mediumprior to filling syringe 18. Subsequently, processor 104 controls motor102 to advance plunger 20 into syringe 18 and discharge the simulatedcontrast medium through outlet port 80 and, in some examples, intocatheter 30. Pressure sensor 100 may measure the pressure of thesimulated contrast medium as the medium is ejected from the syringe soas to generate data indicative of how the discharge pressure of thesimulated contrast medium varies over time during the injection. Forexample, the data may indicate the pressure at outlet port 80 from aninitial time when plunger 20 starts to advance within syringe 18 to afinal time when the plunger stops advancing within the syringe.Processor 104 may receive the data from pressure sensor 100 and storethe data as simulated contrast medium pressure data in memory 108.

The technique of FIG. 6 also includes comparing the active contrastmedium pressure data to the simulated contrast medium pressure data(204). For example, processor 104 may reference memory 108 and comparethe active contrast medium pressure data to the simulated contrastmedium pressure data. In some examples, an average pressure (e.g., meanpressure, median pressure) of the active contrast medium duringinjection is compared to an average pressure of the simulated contrastmedium during injection. In other examples, a maximum or minimumpressure of the active contrast medium during injection is compared to amaximum or minimum pressure of the simulated contrast medium duringinjection. In still other examples, a pressure of the active contrastmedium at a particular time in the injection process is compared to apressure of the simulated contrast medium at the same particular time inthe injection process. The active contrast medium pressure data may becompared to the simulated contrast medium pressure data, for example, bydetermine a difference between a pressure of the active contrast mediumand a corresponding pressure of the simulated contrast medium.

Based on the comparison between the active contrast medium pressure datato the simulated contrast medium pressure data, a concentration of thepolyvinyl alcohol in the simulated contrast medium may be adjusted(206). In different examples, the concentration of the polyvinyl alcoholmay be increased by adding more polyvinyl alcohol to the simulatedcontrast medium or decreased by adding more water to the simulatedcontrast medium. The concentration of the polyvinyl alcohol may beadjusted to increase or decrease a flow property of the simulatedcontrast medium so that flow property is equal or substantially equal toa corresponding flow property of the active contrast medium. In someexamples, the concentration of the polyvinyl alcohol is adjusted until aprofile of pressure versus time as measure during injection for thesimulated contrast media is substantially the same as a profile ofpressure versus time as measured during injection for the activecontrast media. By adjusting the concentration of the polyvinyl alcoholin the simulated contrast medium based on the comparison between theactive contrast medium pressure data and the simulated contrast mediumpressure data, the simulated contrast medium may be formulated toreplicate the flow behavior of the active contrast medium.

The following non-limiting example may provide additional details aboutsimulated contrast media in accordance with this disclosure.

EXAMPLE

Pressure data was generated by injecting 25 milliliters (ml) ofIsovue®-370, a contrast medium containing an organically bound iodineactive contrast agent, at a rate of 8 ml/sec. The injection procedurewas repeated three times to generate three pressure versus timeprofiles. The pressure data used to generate the profiles were measuredduring injection of the contrast medium. The three example pressureversus time profiles are provided as FIGS. 7A-7C. The average maximumpressure for the three injections was 536 psi.

Next, pressure data was generated by injecting 25 milliliters (ml) of asimulated contrast medium at a rate of 8 ml/sec. The simulated contrastmedium included 3.3 wt % polyvinyl alcohol and a balance weightpercentage water. Injection of the simulated contrast medium wasrepeated three times to generate three pressure versus time profiles.The pressure data used to generate the profiles were measured duringinjection of the simulated contrast medium. The three example pressureversus time profiles for the simulated contrast medium are provided asFIGS. 8A-8C. The average maximum pressure for the three injections was504 psi.

Comparison of the average maximum peak pressure of the contrast mediumto the average maximum peak pressure of the simulated contrast mediumrevealed that the pressures differed by 32 psi. In this example, thedesign target for the simulated contrast medium was to have averagemaximum peak pressure of the simulated contrast medium be within a rangeof plus or minus 25 psi of the average maximum peak pressure of thecontrast medium. Accordingly, the concentration of polyvinyl alcohol inthe simulated contrast medium was increased based on the comparisonuntil the simulated contrast medium included 3.8 wt % polyvinyl alcoholand a balance weight percentage water.

Pressure data was generated by injecting 25 milliliters (ml) of aadjusted simulated contrast medium at a rate of 8 ml/sec. Injection ofthe simulated contrast medium was repeated three times to generate threepressure versus time profiles. The pressure data used to generate theprofiles were measured during injection of the adjusted simulatedcontrast medium. The three example pressure versus time profiles for theadjusted simulated contrast medium are provided as FIGS. 9A-9C. Theaverage maximum pressure for the three injections was 534 psi. Based onthe design parameters set forth for the particular simulated contrastmedium in this example, the simulated contrast medium exhibited a flowproperty substantially equal to a corresponding flow property of thecontrast medium with the active contrast agent.

Various examples have been described. These and other examples arewithin the scope of the following claims.

The invention claimed is:
 1. A system comprising: a powered injectorthat includes a plunger, a motor configured to advance and retract theplunger, and a syringe holder configured to hold a syringe so that theplunger moves within the syringe; a fluid reservoir containing asimulated contrast medium in fluid communication with the syringe, thesimulated contrast medium exhibiting a fluid flow property substantiallyequal to that of an active contrast medium but being devoid of anyactive contrast agent that provides contrast during diagnostic imaging;and a processor configured to retract the plunger within the syringe soas to draw the simulated contrast medium from the reservoir into thesyringe and advance the plunger within the syringe so as to dischargethe simulated contrast medium from the syringe.
 2. The system of claim1, wherein the simulated contrast medium is a thixotropic liquid.
 3. Thesystem of claim 1, wherein the active contrast medium comprises iodineand the simulated contrast medium is devoid of iodine.
 4. The system ofclaim 1, wherein the fluid flow property is viscosity.
 5. The system ofclaim 4, wherein the simulated contrast medium exhibits a viscositygreater than approximately 1.5 centipoise.
 6. The system of claim 4,wherein the simulated contrast medium exhibits a viscosity ranging fromapproximately 1.5 centipoise and approximately 25 centipoise.
 7. Thesystem of claim 1, wherein the simulated contrast medium consistsessentially of polyvinyl alcohol and water.
 8. The system of claim 1,wherein the fluid reservoir containing the simulated contrast mediumcomprises a first fluid reservoir and further comprising a second fluidreservoir in fluid communication with the syringe, the second fluidreservoir containing saline.
 9. A method comprising: connecting a fluidreservoir containing a simulated contrast medium to a syringe of apowered injector, the simulated contrast medium exhibiting a fluid flowproperty substantially equal to that of an active contrast medium butbeing devoid of any active contrast agent that provides contrast duringdiagnostic imaging; performing a fill operation by moving, under thecontrol of a processor, a plunger of the powered injector rearward todraw the simulated contrast medium from the fluid reservoir into thesyringe; and performing an injection operation by moving, under thecontrol of the processor, the piston of the powered injector forward todischarge the simulated contrast medium from the syringe.
 10. The methodof claim 9, wherein the simulated contrast medium is a thixotropicliquid.
 11. The method of claim 9, wherein the active contrast mediumcomprises iodine and the simulated contrast medium is devoid of iodine.12. The method of claim 9, wherein the fluid flow property is viscosity.13. The method of claim 12, wherein the simulated contrast mediumexhibits a viscosity ranging from approximately 1.5 centipoise andapproximately 25 centipoise.
 14. The method of claim 9, wherein thesimulated contrast medium consists essentially of polyvinyl alcohol andwater.
 15. The method of claim 9, wherein the fluid reservoir containingthe simulated contrast medium comprises a first fluid reservoir andfurther comprising connecting a second fluid reservoir containing salineto the syringe of a powered injector.
 16. The method of claim 9, whereinperforming the injection operation comprises discharging the simulatedcontrast medium into a waste receptacle.